Method for identifying attenuated chickenpox virus Oka strain or strain originating therein and acceptable as attenuated chickenpox vaccine virus

ABSTRACT

Disclosed is a method for exact identification of the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus, which comprises analyzing the difference in the genomic DNA and fragments thereof between the Oka strain and a sample varicella strain, and determining whether or not a sample strain satisfies all of the following eight characteristics: the sizes of the HpaI-K fragment and the EcoRI-P fragment; the size of R2-487 region of Gene14 and the analysis by PCR-SSCP; the sizes of the restriction fragments obtained by digesting the R2-1764 fragment with AccIII; the absence or presence of a PstI cleavage site; the homology of the amino acid sequences coded by R2-487 coding region; and the homology of the amino acid sequences coded by the coding region of VZV Gene14. The method of the present invention is extremely useful for the quality control and quality assurance of attenuated varicella live vaccines. Also disclosed are an isolated virus strain which is substantially the same virus strain as identified by the above method; an attenuated varicella virus live vaccine comprising the same virus strain as identified by the above method; an attenuated varicella virus Oka strain antigen; and a pair of primers which are advantageously, effectively usable in the above method.

The application claims the benefit under 35 U.S.C. §371 of prior PCT International Application No. PCT/JP97/01646 which has an international filing date of May 15, 1997 which designated the United States of America, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for identifying the attenuated varicella virus Oka strain. More particularly, the present invention relates to a method for identifying the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus, and an isolated virus strain which is substantially the same virus strain as identified as the attenuated varicella virus Oka strain or a strain derived therefrom by the above method. The present invention also relates to an attenuated varicella virus Oka strain antigen. The present invention further relates to a pair of novel primers which are advantageously, effectively usable in the method of the present invention.

2. Prior Art

As is well known, attenuated live varicella vaccines used today are manufactured from a seed strain of varicella-zoster virus (hereinafter, frequently referred to simply as "varicella virus") which is a virus derived from the attenuated varicella virus Oka strain (see Examined Japanese Patent Application Publication No. 53-41202 and U.S. Pat. No. 3,985,615), and the attenuated live vaccines are used widely throughout the world {Requirements for Varicella Vaccine (Live) Adopted 1984: WHO Technical Report Series, No. 725, pp. 102-124, 1985}. To ensure the safety and effectiveness of the vaccine, the number of passages of a virus used for producing the vaccine is under the control of a seed lot system, taking into consideration the potential genetic mutation which is likely to occur during the passage. That is, the manufacturers are under an obligation to produce varicella vaccines only from the virus derived from the approved seed virus for the live varicella vaccine, wherein the number of passages of the virus is not more than 10 as counted from the approved seed virus which is counted as 0 passage. In other words, the quality control and quality assurance of the attenuated live varicella vaccine rely upon the fulfillment of the seed lot system by the manufacturers, and the quality of the vaccine has not been determined by a direct genetic analysis of a seed virus genomic DNA or a vaccine virus genomic DNA.

Further, from the viewpoint of epidemiology which involves a tracing of the effects of a varicella vaccine and a post-market surveillance (PMS), the virological difference between the fresh wild-type strains isolated from the naturally infected varicella patients and the vaccine virus strains derived from the above-mentioned Oka strain needs to be determined, and various methods have been attempted for determination of the virological difference. Since the gene of a VZV genome and the structure of the gene were reported (Journal of General Virology, 67, 1759-1816, 1986), various determination methods of the virological difference based on the differences between the properties and characteristics of the strains, such as the difference in DNA sequence between the different VZV strains (Journal of Virology, 59, 660-668, 1986), the difference in the absence or presence of a restriction enzyme PstI cleavage site (Japanese Journal of Experimental Medicine, 59, 233-237, 1989), the difference in RFLP (restriction fragment length polymorphism) of the PCR (polymerase chain reaction) product (Journal of Virology, 66, 1016-1020, 1992), and the difference in the absence or presence of a restriction enzyme PstI restriction site which is taken in combination with the difference in RFLP of the PCR product (Journal of Clinical Microbiology, 33, 658-660, 1995). However, all of these methods are not sufficient and cannot be used for exact identification of the Oka strain.

In other words, for quality control and quality assurance of the vaccine and from the viewpoint of epidemiology which involves a tracing of the effects of the vaccine and a PMS, it is critically important to identify or determine the above-mentioned attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus (which Oka strain or a strain derived therefrom can be used as an active ingredient of an attenuated live varicella vaccine). However, a method reliable for such identification or determination has not been established, and a development of such a method has been earnestly desired in the art.

SUMMARY OF THE INVENTION

In the above situation, the present inventors have made extensive and intensive studies with a view toward developing a novel method for identifying, with exactness and speediness, the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus. The present inventors have performed an extensive genetic analysis to investigate the difference in genomic DNA between the attenuated varicella virus Oka strain (or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus) and other varicella strains, such as a known varicella strain and a fresh wild-type strain. As a result, they have found that eight specific characteristics described below can be used for identifying the attenuated varicella virus Oka strain (or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus) with exactness and speediness. That is, they have found that exact and speedy identification of the Oka strain or a useful strain derived therefrom can be made by determining whether or not a sample strain satisfies all of the eight characteristics. The present invention has been completed, based on this novel finding.

Therefore, it is an object of the present invention to provide a novel method for identifying the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus, with exactness and speediness.

It is another object of the present invention to provide an isolated virus strain which is substantially the same virus strain as identified, by the above-mentioned method, as the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus.

It is a further object of the present invention to provide an attenuated varicella live vaccine comprising, as an active ingredient, an isolated virus strain which is substantially the same virus strain as identified, by the above-mentioned method, as the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus.

Still a further object of the present invention is to provide an attenuated varicella virus Oka strain antigen comprising a contiguous sequence of at least a part of an amino acid sequence coded by a particular region of the attenuated varicella virus genomic DNA.

Still a further object of the present invention is to provide a pair of novel primers which can be advantageously, effectively used in the method of the present invention.

The foregoing and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description and the appended claims taken in connection with the accompanying sequence listing and drawings.

The Definition and Explanation of the Terminologies Used in the Present Invention

(1) VZV: An abbreviation for "varicella-zoster virus" (hereinafter, frequently referred to simply as "varicella virus") which causes varicella-herpes zoster. The identification method of the present invention may be applied to a virus isolated from a patient suffering from either varicella or zoster.

(2) Varicella vaccine: A vaccine effective for preventing the infection with a VZV or the onset of the disease after the infection.

(3) Attenuated Oka strain: A strain which is equivalent to the attenuated varicella virus Oka strain (see Examined Japanese Patent Application Publication 53-41202 and U.S. Pat. No. 3,985,615). The attenuated Oka strain is deposited under the deposition number VR-795 on Mar. 14, 1975 with ATCC (American Type Culture Collection; 10801 University Boulevard, Mancossas, Va. 20110-2209 ).

(4) Attenuated varicella vaccine virus: A varicella virus derived from the approved seed virus for preparing the live varicella vaccine, wherein the number of passages of the virus is not more than 10 as counted from the approved seed virus which is counted as 0 passage (see WHO Technical Report Series No. 725, pp. 107-108, 1985). An attenuated varicella virus is useful as an active ingredient for a varicella vaccine.

(5) Gene numbers of VZV (Gene14 and Gene38) and the nucleotide numbers of the DNA: These numbers are based on the report by Davison and Scott (Journal of General Virology, 67, 1759-1816, 1986).

(6) The size of a restriction fragment {unit: base pair (bp)}: The size of a restriction fragment having cohesive ends which is obtained by digesting a VZV gene DNA sequence with a restriction enzyme is calculated from the cleavage sites of the restriction enzyme. For example, when the restriction enzyme E cleavage sites are two sites of the 10th nucleotide and the 60th nucleotide of the sequence, the size of the obtained restriction fragment E of the DNA is 60-10=50, namely, 50 bp.

(7) HK fragment: An abbreviation for HpaI-K shown in FIG. 1 (Journal of infectious Diseases, 149, 956-963, 1984; this means the K fragment obtained by digesting a VZV genomic DNA with the restriction enzyme HpaI).

(8) EP fragment: An abbreviation for EcoRI-P shown in FIG. 1 (Journal of Virology, 59, 660-668; this means the P fragment obtained by digesting a VZV genomic DNA with the restriction enzyme EcoRI).

(9) PCR-SSCP: An abbreviation for "Polymerase Chain Reaction-Single Strand Conformation Polymorphism" which is a method for analyzing a DNA fragment, which is amplified by PCR, in accordance with SSCP (Proceedings of National Academy of Science, USA, 86, 2766-2770, 1989).

(10) R2-487 region: A region of a VZV genome comprising the repetitive sequence R2 of Gene14, which region is obtained as a DNA fragment amplified by PCR using the PCR primers (2) and (3) shown in Table 1. The size of the R2-487 region of the attenuated varicella live vaccine virus Oka strain is 487 bp.

(11) R2-1764 region: A region of a VZV genome comprising the repetitive sequence R2 of Gene14, which region is obtained as a DNA fragment amplified by PCR using the PCR primers (1) and (3) shown in Table 1. The size of the R2-1764 region of the attenuated varicella live vaccine virus Oka strain is 1764 bp.

(12) Primers: The names and DNA sequences {described in a direction from left (5') to right (3')} of the PCR primers used in the present invention are shown in the following Table 1:

                                      TABLE 1                                      __________________________________________________________________________     Names of the primers, and DNA sequences thereof                                __________________________________________________________________________     Primer (1):                                                                            5'-GATGGATATAATCCACACCC-3' (sense strand)                                                                    SEQ ID NO:5                                 - Primer (2): 5'-GACGCATGTAACAAGGCATG-3' (sense strand) SEQ ID NO:6                                                 - Primer (3): 5'-TCGACTGAATCTCAACC                                           CAC-3' (antisense strand) SEQ ID                                               NO:7                                        - Primer (4): 5'-GATGTTTCCAAATCTAACTC-3' (antisense strand) SEQ ID                                                NO:8                                        - Primer (PS1): 5'-AAGTTTCAGCCAACGTGCCAATAAA-3' (sense strand) SEQ ID                                             NO:9                                        - Primer (PS2): 5'-AGACGCGCTTAACGGAAGTAACG-3' (antisense strand)            __________________________________________________________________________

As mentioned above, the present inventors have made an investigation, by genetic analysis, on the difference in genomic DNA between the attenuated varicella virus Oka strain (or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus) and other VZV strains, for example, known strains and fresh wild-type strains. The subjects of the genetic analysis can be summarized in (a) to (e) below (see FIG. 1 also):

(a) individually determining the sizes of the HK fragment and the EP fragment;

(b) amplifying the R2-1764 region by PCR to obtain a VZV genomic DNA fragment, and treating the obtained fragment with the restriction enzyme AccIII {A Practical Guide to Molecular Cloning, Second Edition (1988)} to confirm its cleavage into two parts, followed by determining the sizes of the two parts;

(c) amplifying the R2-487 region by PCR to obtain a VZV genomic DNA fragment and determining the size of the DNA fragment, wherein an analysis of the R2-487 region by PCR-SSCP and a determination of the nucleotide sequence of the region are also conducted;

(d) amplifying a part of Gene38 by PCR to obtain a VZV genomic DNA fragment, and treating the obtained fragment with the restriction enzyme PstI, followed by determination of the size of the fragment before and after the treatment to thereby determine whether the fragment is cleaved with PstI or not, wherein the analysis confirms the absence or presence of a restriction enzyme PstI cleavage site; and

(e) amplifying the entire coding region of the VZV Gene14 by PCR, and determining the nucleotide sequence thereof.

The present invention was completed, based on the results of the above-mentioned analyses (a) to (e).

BRIEF DESCRIPTION OF THE SEQUENCE LISTING

SEQ ID NO. 1 is the nucleotide sequence of the R2-487 region of the attenuated Oka strain genomic DNA, and the amino acid sequence (162 amino acid residues) translated from the nucleotide sequence in accordance with the universal code (also set forth in SEQ ID NO:2);

SEQ ID NO. 3 is the nucleotide sequence of the entire coding region of Gene14 (1683 bp), and the amino acid sequence (560 amino acid residues) translated from the nucleotide sequence in accordance with the universal code(also set forth in SEQ ID No:4); and

SEQ ID NOs. 5-10 are the PCR primers used for preparing the DNA fragments of the VZV genomic DNA which are used for identifying the attenuated varicella virus Oka strain.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a diagram of a VZV genomic DNA (approximately 125 kb) showing the location of Gene14, the location and size of the restriction fragments of the genomic DNA of the attenuated Oka strain, and the nucleotide sequence of the primers used in the present invention; and

FIGS. 2A to 2C and FIGS. 3A to 3C show the comparison between the nucleotide and amino acid sequences of the attenuated Oka strain, the sequences disclosed by Davison and Scott (Journal of General Virology, 67, 1759-1816, 1986) and the sequences disclosed by Kinchington et al. (Journal of Virology, 59, 660-668, 1986). Each of the nucleotide sequences of the entire coding region of Gene14 are compared in FIGS. 2A to 2C, and each of the amino acid sequences translated from the nucleotide sequences in accordance with the universal code are compared in FIGS. 3A to 3C.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention, there is provided a novel method for accurately identifying the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus.

For easy understanding of the present invention, the essential features and various preferred embodiments of the present invention are enumerated below.

1. A method for identifying the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus, which comprises:

analyzing a genomic DNA and DNA fragments thereof of a sample varicella virus; and

determining whether the analyzed genomic DNA and DNA fragments thereof of the sample varicella virus satisfy all of the following eight characteristics (A1) to (A8):

(A1) the size of the K fragment obtained by digesting the varicella virus genomic DNA with the restriction enzyme HpaI is 3231 bp;

(A2) the size of the P fragment obtained by digesting the varicella virus genomic DNA with the restriction enzyme EcoRI is 1749 bp;

(A3) when a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer (1) of SEQ ID NO. 5 and the PCR primer (3) of SEQ ID NO. 7 is treated with the restriction enzyme AccIII, the DNA fragment is cleaved into two parts having sizes of 1208 bp and 556 bp, respectively;

(A4) a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer (2) of SEQ ID NO. 6 and the PCR primer (3) of SEQ ID NO. 7 has a size of 487 bp;

(A5) the varicella virus genomic DNA and the attenuated varicella virus Oka strain genomic DNA exhibit substantially the same electrophoretic mobility with respect to a DNA fragment determined by PCR-SSCP wherein the PCR primer (2) of SEQ ID NO. 6 and the PCR primer (3) of SEQ ID NO. 7 are used in the PCR of the PCR-SSCP;

(A6) a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer (PS1) of SEQ ID NO. 9 and the PCR primer (PS2) of SEQ ID NO. 10 lacks a restriction enzyme PstI cleavage site;

(A7) the homology between the 162 amino acid sequence coded by the varicella virus genomic DNA which sequence corresponds to the 162 amino acid sequence of SEQ ID NO. 1, and the 162 amino acid sequence of SEQ ID NO.1 is 98 to 100%; and

(A8) the homology between the 560 amino acid sequence coded by the varicella virus genomic DNA which sequence corresponds to the 560 amino acid sequence of SEQ ID NO. 3, and the 560 amino acid sequence of SEQ ID NO.3 is 99 to 100%.

2. An isolated virus strain which is substantially the same virus strain as identified, by the method of item 1 above, as the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus.

3. An attenuated varicella virus live vaccine comprising, as an active ingredient, an isolated virus strain which is substantially the same virus strain as identified, by the method of item 1 above, as the attenuated varicella virus Oka strain or a strain derived therefrom capable of functioning as an attenuated varicella live vaccine virus.

4. An attenuated varicella virus Oka strain antigen comprising a contiguous sequence of at least 3 amino acids selected from the amino acid sequence of SEQ ID NO. 4.

5. A pair of primers selected from the group consisting of the following (a) to (d):

(a) a pair of primer (1) of SEQ ID NO: 5 and primer (3) of SEQ ID NO: 7;

(b) a pair of primer (1) of SEQ ID NO: 5 and primer (4) of SEQ ID NO: 8;

(c) a pair of primer (2) of SEQ ID NO: 6 and primer (3) of SEQ ID NO: 7; and

(d) a pair of primer (PS1) of SEQ ID NO: 9 and primer (PS2) of SEQ ID NO: 10.

Hereinbelow, the present invention is described in detail.

In the present invention, with respect to the nucleotide sequences, A represents adenine, C represents cytosine, G represents guanine and T represents thymine.

In the present invention, with respect to the amino acid sequences, Ala represents an alanine residue, Arg represents an arginine residue, Asn represents an asparagine residue, Asp represents an aspartic acid residue, Cys represents a cysteine residue, Gln represents a glutamine residue, Glu represents a glutamic acid residue, Gly represents a glycine residue, His represents a histidine residue, Ile represents an isoleucine residue, Leu represents a leucine residue, Lys represents a lysine residue, Met represents a methionine residue, Phe represents a phenylalanine residue, Pro represents a proline residue, Ser represents a serine residue, Thr represents a threonine residue, Trp represents a tryptophan residue, Tyr represents a tyrosine residue and Val represents a valine residue.

(1) Preparation of the HK Fragment and the EP Fragment, and Measurements of Sizes Thereof

The VZV genomic DNA is extracted and purified from the cells infected with the attenuated Oka strain virus, or with vesicle fluid and the like obtained from the naturally infected varicella patient. The extracted DNA is digested with either HpaI or EcoRI, and each of the sizes of the resultant DNA fragments is measured by agarose gel electrophoresis. For propagating the VZV, WI-38 cells and MRC-cells can be used. It is preferred that the vesicle fluid used as a sample for amplifying and preparing a viral genomic DNA of a fresh wild-type strain is obtained from a naturally infected patient within 3 days after the onset of varicella.

(2) Preparation of PCR Primers

A pair of polynucleotide strands consisting of contiguous sequences of about 15 to 30 nucleotides are prepared by a DNA synthesizer, wherein one polynucleotide strand corresponds to the 5'-terminal sequence of the desired region of one of the strands of the VZV genomic DNA to be amplified by PCR, and the other polynucleotide strand corresponds to that of the complementary strand of the above-mentioned strand of the VZV genomic DNA (for example, a sense strand and an antisense strand). The prepared polynucleotide strands are simultaneously used as the PCR primers. The prior art mentioned under "Prior Art" of the specification can be consulted when designing the nucleotide sequences of the polynucleotides for the PCR primers. However, the pairs of primers of the present invention are preferably used. The DNA fragments of a varicella virus genomic DNA analyzed for identifying the attenuated varicella virus Oka strain or a strain derived therefrom are obtained with ease and high accuracy.

(3) Preparation of Fragments Respectively Corresponding to the R2-regions, Determination of Sizes Thereof, and the Analysis of Nucleotide Sequences Thereof

After extracting a VZV genomic DNA directly from a vesicle fluid in the above-mentioned manner, the R2-487 region and R2-1764 region of the extracted DNA are individually amplified by PCR. The size of each of the amplified DNA fragments is determined by agarose gel electrophoresis. The nucleotide sequence can be analyzed by the conventional methods, for example, Dideoxy method, and a method using Cycle Sequence Kit (manufactured and sold by TAKARA SHUZO Co. Ltd., Japan).

With respect to the entire coding region of VZV Gene14, the DNA can be prepared and analyzed in substantially the same manner as mentioned above. The nucleotide sequence of the entire coding region of Gene14 of the attenuated varicella virus Oka strain is shown in SEQ ID NO. 3. This sequence has been elucidated and is disclosed for the first time by the inventors of the present invention.

R2 is a repetitive sequence found in the above-mentioned Gene14, and R2 is contained in both the HK fragment and the EP fragment (see FIG. 1). Further, the amplified R2-1764 region can also be analyzed by RFLP using the restriction enzyme AccIII.

(4) Preparation of a Fragment Corresponding to the Restriction Enzyme PstI Site Region, and Determination of the Absence or Presence of a Restriction Enzyme PstI Cleavage Site

After extracting the VZV genomic DNA directly from a vesicle fluid in the above-mentioned manner, the PstI site region (647 bp) of the extracted DNA is amplified by PCR. The amplified DNA fragment is digested by the restriction enzyme PstI and subjected to agarose gel electrophoresis to determine whether the PstI site region consisting of 647 bp is cleaved into two parts having sizes of 290 bp and 357 bp, respectively. The cleavage of the PstI site region into two parts confirms the existence of a PstI cleavage site in the PstI site region. The genomic DNA of the attenuated Oka strain lacks a PstI cleavage site in the PstI site region thereof and, therefore, the amplified DNA fragment is not cleaved into two parts.

(5) PCR-SSCP

The R2-487 region of the VZV genomic DNA is amplified by PCR using PCR primers labeled with ³² P at their respective 5'-termini, thereby obtaining labeled DNA fragments. Each amplified DNA fragment is subjected to polyacrylamide gel electrophoresis, and the electrophoretic mobility of the fragment is compared with that of the R2-487 region of the attenuated Oka strain.

(6) Vaccine Comprising the Attenuated Oka Strain

The attenuated Oka strain virus or a virus derived therefrom which is identified by the present invention is suitable for the active ingredient of the varicella vaccine, and such a strain can be provided as a varicelia vaccine.

(7) gpV of the Attenuated Varicella Virus Oka Strain Which can be Used as an Antigen for Diagnosis

As apparent from FIGS. 2 and 3, the attenuated varicella Oka strain virus identified by the present invention comprises an amino acid sequence (shown in SEQ ID NO. 4) which is specific for the attenuated varicella virus Oka strain. Therefore, gpV (glycoprotein V) coded by Gene14 of the attenuated varicella virus Oka strain genome can be used advantageously, for example, as an antigen for diagnosis. For example, the necessity of vaccination can be determined from an intracutaneous reaction using the antigen of the present invention. The attenuated varicella virus antigen of the present invention comprises a contiguous sequence of 3 or more amino acids, preferably 5 amino acids, more preferably 7 amino acids selected from the amino acid sequence of SEQ ID NO. 4.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, the present invention will be described in more detail with reference to the following Example, but they should not be construed as limiting the scope of the present invention.

EXAMPLE 1

Kawaguchi strain which is a wild-type VZV strain and the fresh wild-type strains respectively isolated from the vesicle fluids of 9 patients naturally infected with varicella (10 samples in total) were tested as follows. The attenuated Oka strain was used as a control, and the results of the tests with respect to the 10 samples were compared with the results of the tests with respect to the attenuated Oka strain.

Test (1) Determination of the Size of the HK Fragment

The attenuated Oka strain, the Kawaguchi strain and the 9 samples of vesicle fluids respectively obtained from the naturally infected varicella patients, were individually inoculated into MRC-5 cells to obtain infected cells, and the infected cells were cultured. Each of the cell cultures (10⁶ cells) was subjected to low-speed centrifugation at 400×g at 4° C. for 5 minutes to thereby collect the infected cells, and the collected cells were freeze-thawed. Each of the collected cells was individually suspended in 5.0 ml of lysis buffer mentioned below, and treated with 50 μg of each of DNase I and RNase A at 37° C. for 30 minutes, followed by cooling in ice for 10 minutes. Then, to each of the resultant mixtures was added 2.5 ml of trichlorotrifluoroethane and vigorously agitated for 6 minutes, followed by low-speed centrifugation at 400×g at 4° C. for 15 minutes to thereby obtain a supernatant. Each of the obtained supernatants was individually layered on a discontinuous density gradient double-layer composition consisting of 2 layers of 7.5 ml of lysis buffer which respectively contain 5% (V/V) and 40% (V/V) of glycerol, and the resultant material was ultracentrifuged at 100,000×g at 4° C. for 70 minutes, thereby obtaining a precipitate. Each of the obtained precipitates was resuspended in 0.5 ml of STE buffer {1% (W/V) SDS (sodium dodecyl sulfate; 0.05 mM Tris-HCl buffer (pH 7.4); and 10 mM EDTA (2 Na)}, and treated with 500 μg of proteinase K at 65° C. for 3 hours. The resultant mixture was purified by repeating phenol extraction 3 times using an aqueous saturated phenol, followed by ethanol precipitation at -70° C. As a result, the genomic DNA of each of the 10 sample VZV viruses including the Kawaguchi strain and the genomic DNA of the attenuated Oka strain were obtained.

Composition of the Lysis Buffer

Solutes contained in 50 mM Tris-HCl buffer {pH 7.4; Tris is "Tris(hydroxymethyl)aminomethane"} and the concentrations thereof are as follows:

3 mM calcium chloride;

5 mM magnesium acetate;

125 mM potassium chloride;

1 mM EDTA (2Na) (disodium ethylenediaminetetraacetate);

1 mM DTT (dithiothreitol);

0.5% (W/V) SDC (sodium deoxycholate) and

0.5% (W/V) NONIDET P-40 (Octylphenoxyl Polyethoxy ethanol) (manufactured and sold by Sigma Chemical Company, USA).

Each of the genomic DNAs prepared above was digested with the restriction enzyme HpaI, and the size of each of the obtained DNA fragments (HK fragments) was measured by agarose gel electrophoresis in a 0.5% (W/V) agarose gel. As a result, it was found that the size of the HK fragment of the attenuated Oka strain is 3231 bp, and only 3 samples out of the 10 samples tested had the HK fragment having the same size as that of the attenuated Oka strain.

Test (2) Determination of the Size of the EP Fragment

With respect to each of the above-mentioned samples and control, a DNA fragment (EP fragment) was obtained by treating the genomic DNA with the restriction enzyme and the size of the obtained fragment was measured by electrophoresis in substantially the same manner as in Test (1) above, except that the restriction enzyme EcoRI was used instead of HpaI. As a result, it was found that the size of the EP fragment of the attenuated Oka strain is 1749 bp, and only 3 samples out of the 10 samples tested had the EP fragment having the same size as that of the attenuated Oka strain.

Test (3) Determination of the Size and Nucleotide Sequence of the R2-487 Region

The respective genomic DNA fragments of the attenuated Oka strain and Kawaguchi strain were individually prepared from the culture media of the cells infected with the respective strains. The genomic DNA of each of the 9 fresh wild-type strains was directly prepared from the vesicle fluids of the patients. Specifically, VZV genomic DNA was solubilized by treating the vesicle fluid with guanidine thiocyanate in a final concentration of 5.5 M. The solubilized genomic DNA was subjected to a phenol extraction with phenol and then subjected to chloroform/isoamylalcohol extraction, followed by purification by isopropyl alcohol precipitation to thereby obtain a genomic DNA of the fresh wild-type strain.

The R2-487 regions of the above-obtained genomic DNAs were amplified by PCR using the PCR primers (2) and (3) to obtain R2-487 fragments. The size of each of the obtained R2-487 regions was determined by agarose gel electrophoresis in a 4% (W/V) agarose gel. As a result, it was found that the size of the R2-487 region of the attenuated Oka strain is 487 bp, and only 5 samples out of the 10 samples tested had the R2-487 region having the same size as that of the attenuated Oka strain.

Further, the nucleotide sequence of each of the R2-487 regions was determined by Cycle Sequence Kit (manufactured and sold by TAKARA SHUZO Co. Ltd., Japan; Manual Code No. R014). The nucleotide sequences of the R2-487 regions of the samples were individually compared with the nucleotide sequence of the attenuated Oka strain to determine the DNA homology between the nucleotide sequences, and also, the amino acid sequences of the R2-487 regions of the samples which were obtained by translating the nucleotide sequences in accordance with the universal code were individually compared with that of the Oka strain to determine the homology between the amino acid sequences. The determination was performed by a computer software for gene analysis {GENETYX (ver. 9.0)(A computer Software for analyzing genes and proteins; manufactured and sold by Software Development Co., Ltd., Japan}. The nucleotide sequence and amino acid sequence of the R2-487 region of the attenuated Oka strain are shown in SEQ ID NO. 1.

The comparison between the nucleotide sequence of the R2-487 region of the attenuated Oka strain and the nucleotide sequence of each of the 10 samples including the Kawaguchi strain shows that a difference in nucleotides was found with respect to 4 or more nucleotides in the R2-487 region of each of the samples, and that this difference in the nucleotides was accompanied by a change in amino acids (coded by 162 codons, i.e., 162 codons=487 bp/3). Thus, the homology between the amino acid sequence of the attenuated Oka strain and that of each of the 10 samples was less than 98% {i.e., 487 bp/3=162 codons; [(162 codons-4 different codons)/162 codons]×100=97.5% <98%}.

Test (4) Determination of the Size of the R2-1764 Region

The genomic DNA of each of the viruses was prepared in substantially the same manner as mentioned in Test (3) above, and each of the R2-1764 regions of the genomic DNAs was individually amplified by PCR using the PCR primers (1) and (3), to thereby obtain the R2-1764 fragments. Each of the obtained R2-1764 fragments was digested with the restriction enzyme AccIII, and the size of each of the digested DNA fragments was determined by agarose gel electrophoresis in a 4% (W/V) agarose gel. As a result, it was found that the R2-1764 fragment of the attenuated Oka strain is cleaved into two parts having sizes of 1208 bp and 556 bp, respectively, and only 5 samples out of the 10 samples tested showed the same restriction pattern as that of the attenuated Oka strain.

Test (5) Determination of the Absence or Presence of a Restriction Enzyme PstI Cleavage Site

The respective genomic DNA fragments of the attenuated Oka strain and Kawaguchi strain were individually prepared from the culture media of the cells infected with the respective strains. The genomic DNA of each of the 9 fresh wild-type strains was directly prepared from the vesicle fluids of the patients. Specifically, the VZV genomic DNA was obtained in substantially the same manner as mentioned in Test (3) above.

The PstI site region (647 bp) of each of the above-prepared genomic DNAS was individually amplified by PCR using the PCR primers (PS1) and (P2). Each of the PCR products was treated with the restriction enzyme PstI, followed by agarose gel electrophoresis in a 4% (W/V) agarose gel to determine the absence or presence of a restriction enzyme PstI cleavage site. As a result, it was found that the PstI site fragment (647 bp) of each of the attenuated Oka strain and Kawaguchi strain was not cleaved into two parts, thus confirming the absence of the PstI cleavage site. The PstI site fragment of each of the other 9 samples was cleaved into two parts having sizes of 290 bp and 357 bp, respectively. By the cleavage of the PstI site region, the presence of a PstI cleavage site was confirmed.

Test (6) Analysis by PCR-SSCP

The R2-487 region of each of the 10 samples and control was amplified and prepared in substantially the same manner as mentioned in Test (3) above, except that the PCR primers (2) and (3) individually labeled with ³² P at respective 5' termini thereof were used instead of the non-labeled primers. Each of the PCR products was denatured by heating at 95° C. for 2 minutes and then, subjected to polyacrylamide gel electrophoresis in a 5% (W/V) polyacrylamide gel to thereby determine the electrophoretic mobility of each of the PCR products. As a result, it was found that none of the PCR products prepared from the genomic DNAs of the samples exhibited substantially the same electrophoretic mobility as the PCR product prepared from the genomic DNA of the attenuated Oka strain, and it was confirmed that none of the 10 sample virus strains are the attenuated Oka strain virus.

Test (7) Analysis of the Nucleotide Sequence of Gene14 of the Attenuated Oka Strain Genomic DNA

A fragment corresponding to the entire coding region of Gene14 was prepared from the genomic DNA of the attenuated Oka strain by PCR using the PCR primers (1) and (4). The nucleotide sequence of the amplified DNA was analyzed by a DNA sequencer (manufactured and sold by LI-cor, USA). The nucleotide sequence of the entire coding region of Gene14 of the attenuated Oka strain determined above is shown in SEQ ID NO. 3.

Further, the amino acid homology between the amino acid sequence of SEQ ID NO. 4 and each of the sequences disclosed in the prior art (Davison and Scott, Journal of General Virology, 67, 1759-1816, 1986; and Kinchington et al., Journal of Virology, 59, 660-668, 1986) was analyzed in substantially the same manner as mentioned in Test (3) above. The results are shown in FIGS. 2 and 3 and 2B. The comparison between the amino acid sequences shown in FIG. 2B shows that the differences in 8 amino acids (for Davison et al.) and 9 amino acids (for Kinchington) were found between the amino acid sequences and, therefore, the amino acid homology between the amino acid sequence of the attenuated Oka strain and each of the prior art sequences was less than 99% {i.e., [(560 a.a.-8 a.a.)/560 a.a.]×100=98.6% for Davison, and [(560 a.a.-9 a.a.)/560 a.a.]×100=98.4% for Kinchington}. Further, it was confirmed that both of the two VZV strains disclosed in the prior art had a restriction enzyme PstI cleavage site mentioned in Test (5) above.

The results of Tests (1) to (7) are summarized in Table 2 below.

                  TABLE 2                                                          ______________________________________                                                                Number of samples                                          which do not satisfy                                                           the characteristics                                                           Specific characteristics (denominator is total                                 satisfied by the attenuated number of different                                Oka strain samples)                                                          ______________________________________                                         Size of HK fragment [3231 bp]                                                                          7/10                                                     Size of EP fragment [1749 bp]  7/10                                            R2-1764 region                                                                 Size of AccIII fragment                                                        [1764 bp→1208 bp + 556 bp]  5/10                                        R2-487 region                                                                  Size [487 bp]  5/10                                                            PCR-SSCP 10/10                                                                 [electrophoretic mobility as                                                   seen in the gel]                                                               Amino acid sequence [homology: 98% or more] 10/10                               (less than 98%)                                                               PstI site region [647 bp]                                                      PstI fragment [present, i.e., 647 bp→                                   [absent, 290 bp + 357 bp]                                                      i.e. fragment size = 647 bp]                                                   PstI restriction [absent] 9/10 (present)                                       Gene14 coding region [1680 bp]                                                 Number of amino acid residues (560)                                            Amino acid sequence [homology: 99% or more]  2/2                                (less than 99%)                                                             ______________________________________                                    

As apparent from the above, by determining whether or not all of the above-mentioned 8 characteristics are satisfied, the attenuated Oka strain can be distinguished from other VZV strains and identified with extremely high accuracy.

INDUSTRIAL APPLICABILITY

According to the method of the present invention, an exact quality control and quality assurance of the attenuated varicella live vaccines used today in the production thereof is achieved. Further, exact and advantageous techniques which can be used in researches in the field of epidemiology of varicella and zoster, including a tracing of the effects of the vaccine and a PMS are provided. Consequently, the present invention provides an exact and very effective measure for preventing varicella and zoster, which contributes to the health of human beings.

    __________________________________________________________________________     #             SEQUENCE LISTING                                                    - -  - - (1) GENERAL INFORMATION:                                              - -    (iii) NUMBER OF SEQUENCES: 10                                           - -  - - (2) INFORMATION FOR SEQ ID NO:1:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 487 base - #pairs                                                  (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: double                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA (genomic)                                      - -     (vi) ORIGINAL SOURCE:                                                           (A) ORGANISM: varicella-zo - #ster virus                                       (B) STRAIN: attenuated - #varicella virus Oka strain                  - -     (ix) FEATURE:                                                                   (A) NAME/KEY: CDS                                                              (B) LOCATION: 1..486                                                  - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                - - TCG ACT GAA TCT CAA CCC ACA CCC GTA AGT AT - #A ATT GAA TTA TAT         ACC       48                                                                     Ser Thr Glu Ser Gln Pro Thr Pro Val Ser Il - #e Ile Glu Leu Tyr Thr             1               5 - #                 10 - #                 15               - - TCG GCC GCT TCC CGA AAG CCC GAT CCC GCC GT - #C GCG CCC ACC TCG GCC            96                                                                        Ser Ala Ala Ser Arg Lys Pro Asp Pro Ala Va - #l Ala Pro Thr Ser Ala                         20     - #             25     - #             30                   - - GCT TCC CGA AAG CCC GAT CCC GCC GTC GCG CC - #C ACC TCG GCC GCT TCC           144                                                                        Ala Ser Arg Lys Pro Asp Pro Ala Val Ala Pr - #o Thr Ser Ala Ala Ser                     35         - #         40         - #         45                       - - CGA AAG CCC GAT CCC GCC GTC GCG CCC ACC TC - #G GCC GCT TCC CGA AAG           192                                                                        Arg Lys Pro Asp Pro Ala Val Ala Pro Thr Se - #r Ala Ala Ser Arg Lys                 50             - #     55             - #     60                           - - CCC GAT CCC GCC GTC GCG CCC ACC TCG GCC GC - #T ACC CGA AAT CCC GAT           240                                                                        Pro Asp Pro Ala Val Ala Pro Thr Ser Ala Al - #a Thr Arg Asn Pro Asp             65                 - # 70                 - # 75                 - # 80        - - CCC GCC GTC GCG CCC ACC TCG GCC GCT TCC CG - #A AAT CCC GAT CCC GCC           288                                                                        Pro Ala Val Ala Pro Thr Ser Ala Ala Ser Ar - #g Asn Pro Asp Pro Ala                             85 - #                 90 - #                 95               - - GTC GCG CCC ACC TCG GCC GCT TCC CGA AAT CC - #C GAT CCC GCC GTC GCG           336                                                                        Val Ala Pro Thr Ser Ala Ala Ser Arg Asn Pr - #o Asp Pro Ala Val Ala                        100      - #           105      - #           110                   - - CCC ACC TCG GCC GCT ACC CGA AAG CCC GAT CC - #C GCA GCC AAC GCC CAA           384                                                                        Pro Thr Ser Ala Ala Thr Arg Lys Pro Asp Pr - #o Ala Ala Asn Ala Gln                    115          - #       120          - #       125                       - - CAT TCA CAA CCA CCT TTT CTA TTT GAA AAT AT - #A CAA TGC GTT CAC GGC           432                                                                        His Ser Gln Pro Pro Phe Leu Phe Glu Asn Il - #e Gln Cys Val His Gly                130              - #   135              - #   140                           - - GGA ATA CAA TCC ATA CCC TAT TTT CAC ACA TT - #T ATC ATG CCT TGT TAC           480                                                                        Gly Ile Gln Ser Ile Pro Tyr Phe His Thr Ph - #e Ile Met Pro Cys Tyr            145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - ATG CGT C               - #                  - #                        - #         487                                                                  Met Arg                                                                         - -  - - (2) INFORMATION FOR SEQ ID NO:2:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 162 amino - #acids                                                 (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: protein                                            - -     (vi) ORIGINAL SOURCE:                                                           (A) ORGANISM: varicella-zo - #ster virus                                       (B) STRAIN: attenuated - #varicella virus Oka strain                  - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                - - Ser Thr Glu Ser Gln Pro Thr Pro Val Ser Il - #e Ile Glu Leu Tyr         Thr                                                                                1               5 - #                 10 - #                 15              - - Ser Ala Ala Ser Arg Lys Pro Asp Pro Ala Va - #l Ala Pro Thr Ser Ala                    20     - #             25     - #             30                   - - Ala Ser Arg Lys Pro Asp Pro Ala Val Ala Pr - #o Thr Ser Ala Ala Ser                35         - #         40         - #         45                       - - Arg Lys Pro Asp Pro Ala Val Ala Pro Thr Se - #r Ala Ala Ser Arg Lys            50             - #     55             - #     60                           - - Pro Asp Pro Ala Val Ala Pro Thr Ser Ala Al - #a Thr Arg Asn Pro Asp        65                 - # 70                 - # 75                 - # 80        - - Pro Ala Val Ala Pro Thr Ser Ala Ala Ser Ar - #g Asn Pro Asp Pro Ala                        85 - #                 90 - #                 95               - - Val Ala Pro Thr Ser Ala Ala Ser Arg Asn Pr - #o Asp Pro Ala Val Ala                   100      - #           105      - #           110                   - - Pro Thr Ser Ala Ala Thr Arg Lys Pro Asp Pr - #o Ala Ala Asn Ala Gln               115          - #       120          - #       125                       - - His Ser Gln Pro Pro Phe Leu Phe Glu Asn Il - #e Gln Cys Val His Gly           130              - #   135              - #   140                           - - Gly Ile Gln Ser Ile Pro Tyr Phe His Thr Ph - #e Ile Met Pro Cys Tyr       145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - Met Arg                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:3:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 1683 base - #pairs                                                 (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: double                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: DNA (genomic)                                      - -     (vi) ORIGINAL SOURCE:                                                           (A) ORGANISM: varicella-zo - #ster virus                                       (B) STRAIN: attenuated - #varicella virus Oka strain                  - -     (ix) FEATURE:                                                                   (A) NAME/KEY: CDS                                                              (B) LOCATION: 1..1683                                                 - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                - - ATG AAG CGG ATA CAA ATA AAT TTA ATT TTA AC - #G ATC GCG TGT ATA         CAA       48                                                                     Met Lys Arg Ile Gln Ile Asn Leu Ile Leu Th - #r Ile Ala Cys Ile Gln                   165          - #       170          - #       175                       - - TTA TCG ACT GAA TCT CAA CCC ACA CCC GTA AG - #T ATA ATT GAA TTA TAT            96                                                                        Leu Ser Thr Glu Ser Gln Pro Thr Pro Val Se - #r Ile Ile Glu Leu Tyr                180              - #   185              - #   190                           - - ACC TCG GCC GCT TCC CGA AAG CCC GAT CCC GC - #C GTC GCG CCC ACC TCG           144                                                                        Thr Ser Ala Ala Ser Arg Lys Pro Asp Pro Al - #a Val Ala Pro Thr Ser            195                 2 - #00                 2 - #05                 2 -       #10                                                                               - - GCC GCT TCC CGA AAG CCC GAT CCC GCC GTC GC - #G CCC ACC TCG GCC         GCT      192                                                                     Ala Ala Ser Arg Lys Pro Asp Pro Ala Val Al - #a Pro Thr Ser Ala Ala                           215  - #               220  - #               225               - - TCC CGA AAG CCC GAT CCC GCC GTC GCG CCC AC - #C TCG GCC GCT TCC CGA           240                                                                        Ser Arg Lys Pro Asp Pro Ala Val Ala Pro Th - #r Ser Ala Ala Ser Arg                        230      - #           235      - #           240                   - - AAG CCC GAT CCC GCC GTC GCG CCC ACC TCG GC - #C GCT ACC CGA AAT CCC           288                                                                        Lys Pro Asp Pro Ala Val Ala Pro Thr Ser Al - #a Ala Thr Arg Asn Pro                    245          - #       250          - #       255                       - - GAT CCC GCC GTC GCG CCC ACC TCG GCC GCT TC - #C CGA AAT CCC GAT CCC           336                                                                        Asp Pro Ala Val Ala Pro Thr Ser Ala Ala Se - #r Arg Asn Pro Asp Pro                260              - #   265              - #   270                           - - GCC GTC GCG CCC ACC TCG GCC GCT TCC CGA AA - #T CCC GAT CCC GCC GTC           384                                                                        Ala Val Ala Pro Thr Ser Ala Ala Ser Arg As - #n Pro Asp Pro Ala Val            275                 2 - #80                 2 - #85                 2 -       #90                                                                               - - GCG CCC ACC TCG GCC GCT ACC CGA AAG CCC GA - #T CCC GCA GCC AAC         GCC      432                                                                     Ala Pro Thr Ser Ala Ala Thr Arg Lys Pro As - #p Pro Ala Ala Asn Ala                           295  - #               300  - #               305               - - CAA CAT TCA CAA CCA CCT TTT CTA TTT GAA AA - #T ATA CAA TGC GTT CAC           480                                                                        Gln His Ser Gln Pro Pro Phe Leu Phe Glu As - #n Ile Gln Cys Val His                        310      - #           315      - #           320                   - - GGC GGA ATA CAA TCC ATA CCC TAT TTT CAC AC - #A TTT ATC ATG CCT TGT           528                                                                        Gly Gly Ile Gln Ser Ile Pro Tyr Phe His Th - #r Phe Ile Met Pro Cys                    325          - #       330          - #       335                       - - TAC ATG CGT CTA ACG ACC GGA CAA CAG GCG GC - #C TTT AAG CAG CAA CAA           576                                                                        Tyr Met Arg Leu Thr Thr Gly Gln Gln Ala Al - #a Phe Lys Gln Gln Gln                340              - #   345              - #   350                           - - AAA ACA TAT GAA CAA TAT TCT TTA GAT CCG GA - #A GGT TCA AAT ATA ACA           624                                                                        Lys Thr Tyr Glu Gln Tyr Ser Leu Asp Pro Gl - #u Gly Ser Asn Ile Thr            355                 3 - #60                 3 - #65                 3 -       #70                                                                               - - AGG TGG AAG TCG CTT ATA CGC CCC GAT CTT CA - #T ATT GAA GTT TGG         TTT      672                                                                     Arg Trp Lys Ser Leu Ile Arg Pro Asp Leu Hi - #s Ile Glu Val Trp Phe                           375  - #               380  - #               385               - - ACG CGT CAC CTT ATA GAT CCG CAC CGT CAA CT - #G GGC AAT GCG TTA ATA           720                                                                        Thr Arg His Leu Ile Asp Pro His Arg Gln Le - #u Gly Asn Ala Leu Ile                        390      - #           395      - #           400                   - - CGC ATG CCA GAT TTA CCG GTT ATG TTA TAT AG - #C AAC AGT GCC GAT TTA           768                                                                        Arg Met Pro Asp Leu Pro Val Met Leu Tyr Se - #r Asn Ser Ala Asp Leu                    405          - #       410          - #       415                       - - AAC TTA ATA AAC AAC CCT GAG ATA TTT ACA CA - #C GCT AAG GAA AAT TAT           816                                                                        Asn Leu Ile Asn Asn Pro Glu Ile Phe Thr Hi - #s Ala Lys Glu Asn Tyr                420              - #   425              - #   430                           - - GTA ATA CCA GAT GTT AAA ACA ACG TCT GAT TT - #T TCT GTA ACA ATT TTA           864                                                                        Val Ile Pro Asp Val Lys Thr Thr Ser Asp Ph - #e Ser Val Thr Ile Leu            435                 4 - #40                 4 - #45                 4 -       #50                                                                               - - TCT ATG GAT GCT ACC ACG GAG GGA ACG TAT AT - #T TGG CGA GTC GTT         AAT      912                                                                     Ser Met Asp Ala Thr Thr Glu Gly Thr Tyr Il - #e Trp Arg Val Val Asn                           455  - #               460  - #               465               - - ACA AAA ACT AAG AAC GTC ATA TCG GAA CAC AG - #T ATT ACA GTT ACA ACG           960                                                                        Thr Lys Thr Lys Asn Val Ile Ser Glu His Se - #r Ile Thr Val Thr Thr                        470      - #           475      - #           480                   - - TAT TAT CGT CCA AAT ATT ACC GTT GTC GGC GA - #T CCA GTC TTA ACC GGA          1008                                                                        Tyr Tyr Arg Pro Asn Ile Thr Val Val Gly As - #p Pro Val Leu Thr Gly                    485          - #       490          - #       495                       - - CAG ACA TAC GCA GCC TAC TGT AAC GTA TCA AA - #G TAT TAT CCA CCG CAC          1056                                                                        Gln Thr Tyr Ala Ala Tyr Cys Asn Val Ser Ly - #s Tyr Tyr Pro Pro His                500              - #   505              - #   510                           - - TCG GTA CGT GTT CGG TGG ACT TCA AGG TTT GG - #T AAC ATC GGA AAA AAT          1104                                                                        Ser Val Arg Val Arg Trp Thr Ser Arg Phe Gl - #y Asn Ile Gly Lys Asn            515                 5 - #20                 5 - #25                 5 -       #30                                                                               - - TTT ATA ACC GAT GCA ATA CAA GAA TAT GCC AA - #T GGA TTA TTT AGT         TAT     1152                                                                     Phe Ile Thr Asp Ala Ile Gln Glu Tyr Ala As - #n Gly Leu Phe Ser Tyr                           535  - #               540  - #               545               - - GTT TCG GCG GTA CGA ATT CCA CAG CAA AAA CA - #A ATG GAT TAC CCA CCC          1200                                                                        Val Ser Ala Val Arg Ile Pro Gln Gln Lys Gl - #n Met Asp Tyr Pro Pro                        550      - #           555      - #           560                   - - CCA GCC ATC CAA TGT AAT GTT TTA TGG ATT CG - #G GAT GGC GTC TCT AAT          1248                                                                        Pro Ala Ile Gln Cys Asn Val Leu Trp Ile Ar - #g Asp Gly Val Ser Asn                    565          - #       570          - #       575                       - - ATG AAA TAT TCT GCT GTC GTT ACC CCT GAC GT - #C TAT CCA TTT CCC AAC          1296                                                                        Met Lys Tyr Ser Ala Val Val Thr Pro Asp Va - #l Tyr Pro Phe Pro Asn                580              - #   585              - #   590                           - - GTG TCT ATA GGT ATT ATT GAT GGA CAC ATA GT - #A TGT ACG GCA AAA TGT          1344                                                                        Val Ser Ile Gly Ile Ile Asp Gly His Ile Va - #l Cys Thr Ala Lys Cys            595                 6 - #00                 6 - #05                 6 -       #10                                                                               - - GTG CCA CGT GGC GTT GTA CAT TTC GTA TGG TG - #G GTT AAC GAT TCT         CCC     1392                                                                     Val Pro Arg Gly Val Val His Phe Val Trp Tr - #p Val Asn Asp Ser Pro                           615  - #               620  - #               625               - - ATC AAC CAC GAA AAC AGT GAG ATT ACT GGG GT - #G TGT GAT CAA AAC AAA          1440                                                                        Ile Asn His Glu Asn Ser Glu Ile Thr Gly Va - #l Cys Asp Gln Asn Lys                        630      - #           635      - #           640                   - - CGG TTT GTA AAC ATG CAA AGT TCT TGT CCA AC - #A TCG GAA CTC GAC GGA          1488                                                                        Arg Phe Val Asn Met Gln Ser Ser Cys Pro Th - #r Ser Glu Leu Asp Gly                    645          - #       650          - #       655                       - - CCT ATC ACC TAT TCG TGT CAT CTA GAT GGT TA - #C CCT AAA AAA TTC CCT          1536                                                                        Pro Ile Thr Tyr Ser Cys His Leu Asp Gly Ty - #r Pro Lys Lys Phe Pro                660              - #   665              - #   670                           - - CCG TTT TCG GCC GTT TAT ACC TAC GAT GCA TC - #T ACC TAC GCC ACT ACA          1584                                                                        Pro Phe Ser Ala Val Tyr Thr Tyr Asp Ala Se - #r Thr Tyr Ala Thr Thr            675                 6 - #80                 6 - #85                 6 -       #90                                                                               - - TTT TCC GTT GTA GCA GTT ATA ATT GGT GTG AT - #A TCT ATC CTT GGG         ACA     1632                                                                     Phe Ser Val Val Ala Val Ile Ile Gly Val Il - #e Ser Ile Leu Gly Thr                           695  - #               700  - #               705               - - TTG GGT CTT ATC GCA GTT ATC GCA ACC CTA TG - #C ATC CGT TGC TGT TCA          1680                                                                        Leu Gly Leu Ile Ala Val Ile Ala Thr Leu Cy - #s Ile Arg Cys Cys Ser                        710      - #           715      - #           720                   - - TAA                  - #                  - #                  - #                1683                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:4:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH:  560 ami - #no acids                                               (B) TYPE: amino acid                                                           (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: protein                                            - -     (vi) ORIGINAL SOURCE:                                                           (A) ORGANISM: varicella-zo - #ster virus                                       (B) STRAIN: attenuated - #varicella virus Oka strain                  - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                - - Met Lys Arg Ile Gln Ile Asn Leu Ile Leu Th - #r Ile Ala Cys Ile Gln         1               5 - #                 10 - #                 15               - - Leu Ser Thr Glu Ser Gln Pro Thr Pro Val Se - #r Ile Ile Glu Leu Tyr                    20     - #             25     - #             30                   - - Thr Ser Ala Ala Ser Arg Lys Pro Asp Pro Al - #a Val Ala Pro Thr Ser                35         - #         40         - #         45                       - - Ala Ala Ser Arg Lys Pro Asp Pro Ala Val Al - #a Pro Thr Ser Ala Ala            50             - #     55             - #     60                           - - Ser Arg Lys Pro Asp Pro Ala Val Ala Pro Th - #r Ser Ala Ala Ser Arg        65                 - # 70                 - # 75                 - # 80        - - Lys Pro Asp Pro Ala Val Ala Pro Thr Ser Al - #a Ala Thr Arg Asn Pro                        85 - #                 90 - #                 95               - - Asp Pro Ala Val Ala Pro Thr Ser Ala Ala Se - #r Arg Asn Pro Asp Pro                   100      - #           105      - #           110                   - - Ala Val Ala Pro Thr Ser Ala Ala Ser Arg As - #n Pro Asp Pro Ala Val               115          - #       120          - #       125                       - - Ala Pro Thr Ser Ala Ala Thr Arg Lys Pro As - #p Pro Ala Ala Asn Ala           130              - #   135              - #   140                           - - Gln His Ser Gln Pro Pro Phe Leu Phe Glu As - #n Ile Gln Cys Val His       145                 1 - #50                 1 - #55                 1 -       #60                                                                               - - Gly Gly Ile Gln Ser Ile Pro Tyr Phe His Th - #r Phe Ile Met Pro         Cys                                                                                              165  - #               170  - #               175              - - Tyr Met Arg Leu Thr Thr Gly Gln Gln Ala Al - #a Phe Lys Gln Gln Gln                   180      - #           185      - #           190                   - - Lys Thr Tyr Glu Gln Tyr Ser Leu Asp Pro Gl - #u Gly Ser Asn Ile Thr               195          - #       200          - #       205                       - - Arg Trp Lys Ser Leu Ile Arg Pro Asp Leu Hi - #s Ile Glu Val Trp Phe           210              - #   215              - #   220                           - - Thr Arg His Leu Ile Asp Pro His Arg Gln Le - #u Gly Asn Ala Leu Ile       225                 2 - #30                 2 - #35                 2 -       #40                                                                               - - Arg Met Pro Asp Leu Pro Val Met Leu Tyr Se - #r Asn Ser Ala Asp         Leu                                                                                              245  - #               250  - #               255              - - Asn Leu Ile Asn Asn Pro Glu Ile Phe Thr Hi - #s Ala Lys Glu Asn Tyr                   260      - #           265      - #           270                   - - Val Ile Pro Asp Val Lys Thr Thr Ser Asp Ph - #e Ser Val Thr Ile Leu               275          - #       280          - #       285                       - - Ser Met Asp Ala Thr Thr Glu Gly Thr Tyr Il - #e Trp Arg Val Val Asn           290              - #   295              - #   300                           - - Thr Lys Thr Lys Asn Val Ile Ser Glu His Se - #r Ile Thr Val Thr Thr       305                 3 - #10                 3 - #15                 3 -       #20                                                                               - - Tyr Tyr Arg Pro Asn Ile Thr Val Val Gly As - #p Pro Val Leu Thr         Gly                                                                                              325  - #               330  - #               335              - - Gln Thr Tyr Ala Ala Tyr Cys Asn Val Ser Ly - #s Tyr Tyr Pro Pro His                   340      - #           345      - #           350                   - - Ser Val Arg Val Arg Trp Thr Ser Arg Phe Gl - #y Asn Ile Gly Lys Asn               355          - #       360          - #       365                       - - Phe Ile Thr Asp Ala Ile Gln Glu Tyr Ala As - #n Gly Leu Phe Ser Tyr           370              - #   375              - #   380                           - - Val Ser Ala Val Arg Ile Pro Gln Gln Lys Gl - #n Met Asp Tyr Pro Pro       385                 3 - #90                 3 - #95                 4 -       #00                                                                               - - Pro Ala Ile Gln Cys Asn Val Leu Trp Ile Ar - #g Asp Gly Val Ser         Asn                                                                                              405  - #               410  - #               415              - - Met Lys Tyr Ser Ala Val Val Thr Pro Asp Va - #l Tyr Pro Phe Pro Asn                   420      - #           425      - #           430                   - - Val Ser Ile Gly Ile Ile Asp Gly His Ile Va - #l Cys Thr Ala Lys Cys               435          - #       440          - #       445                       - - Val Pro Arg Gly Val Val His Phe Val Trp Tr - #p Val Asn Asp Ser Pro           450              - #   455              - #   460                           - - Ile Asn His Glu Asn Ser Glu Ile Thr Gly Va - #l Cys Asp Gln Asn Lys       465                 4 - #70                 4 - #75                 4 -       #80                                                                               - - Arg Phe Val Asn Met Gln Ser Ser Cys Pro Th - #r Ser Glu Leu Asp         Gly                                                                                              485  - #               490  - #               495              - - Pro Ile Thr Tyr Ser Cys His Leu Asp Gly Ty - #r Pro Lys Lys Phe Pro                   500      - #           505      - #           510                   - - Pro Phe Ser Ala Val Tyr Thr Tyr Asp Ala Se - #r Thr Tyr Ala Thr Thr               515          - #       520          - #       525                       - - Phe Ser Val Val Ala Val Ile Ile Gly Val Il - #e Ser Ile Leu Gly Thr           530              - #   535              - #   540                           - - Leu Gly Leu Ile Ala Val Ile Ala Thr Leu Cy - #s Ile Arg Cys Cys Ser       545                 5 - #50                 5 - #55                 5 -       #60                                                                               - -  - - (2) INFORMATION FOR SEQ ID NO:5:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"             - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                - - GATGGATATA ATCCACACCC            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:6:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"              - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                - - GACGCATGTA ACAAGGCATG            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:7:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"              - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                - - TCGACTGAAT CTCAACCCAC            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:8:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 20 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"              - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                - - GATGTTTCCA AATCTAACTC            - #                  - #                       - # 20                                                                    - -  - - (2) INFORMATION FOR SEQ ID NO:9:                                      - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 25 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"              - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                - - AAGTTTCAGC CAACGTGCCA ATAAA          - #                  - #                    25                                                                       - -  - - (2) INFORMATION FOR SEQ ID NO:10:                                     - -      (i) SEQUENCE CHARACTERISTICS:                                                  (A) LENGTH: 23 base - #pairs                                                   (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                  - -     (ii) MOLECULE TYPE: other nucleic acid                                          (A) DESCRIPTION: /desc - #= "Synthesized DNA PCR primer"              - -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                               - - AGACGCGCTT AACGGAAGTA ACG           - #                  - #                     23                                                                     __________________________________________________________________________ 

We claim:
 1. A method for identifying the attenuated varicella virus Oka strain or a strain derived therefrom which functions as an effective component of an attenuated variceila vaccine, which comprises:analyzing a genomic DNA and DNA fragments thereof present in a sample of varicella virus; determining whether the analyzed genomic DNA and DNA fragments thereof of said sample of varicella virus satisfy eight characteristics (A1) to (A8) defined below; and identifying said sample of varicella virus as the attenuated varicella virus Oka strain or a strain derived therefrom which functions as an effective component of an attenuated varicella live vaccine when said sample satisfies all of the following eight characteristics (A1) to (A8):(A1) the size of the K fragment obtained by digesting the varicella virus genomic DNA with the restriction enzyme HpaI is 3231 bp; (A2) the size of the P fragment obtained by digesting the varicella virus genomic DNA with the restriction enzyme EcoRI is 1749 bp; (A3) when a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer 1 (SEQ ID NO. 3) and the PCR primer 3 (SEQ ID NO. 5) is treated with the restriction enzyme AccIII, the DNA fragment is cleaved into two parts having sizes of 1208 bp and 556 bp, respectively; (A4) a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer 2 (SEQ ID NO. 4) and the PCR primer 3 (SEQ ID NO. 5) has a size of 487 bp; (A5) the varicella virus genomic DNA and the attentuated varicella virus Oka strain genomic DNA exhibit substantially the same electrophoretic mobility with respect to a DNA fragment determined by PCR-SSCP wherein the PCR primer 2 (SEQ ID NO. 4) and the PCR primer 3 (SEQ ID NO. 5) are used in the PCR of said PCR-SSCP; (A6) a DNA fragment which is amplified from the varicella virus genomic DNA by PCR using the PCR primer PS1 (SEQ ID NO. 7) and the PCR primer PS2 (SEQ ID NO. 8) lacks a restriction enzyme PstI cleavage site; (A7) the homology between the 162 amino acid sequence coded by the 487 bp DNA fragment amplified from the varicella virus genomic DNA by PCR using the PCR primer 2 (SEQ ID NO. 4) and the PCR primer 3 (SEQ ID NO. 5), and the 162 amino acid sequence of SEQ ID NO. 1 is 98 to 100%, wherein the percent homology is represented by the following formula (1):

    {(162-n)/162×100                                     (1)

wherein n represents the number of different amino acids; and (A8) the homology between the 560 amino acid sequence coded by the entire coding region of Gene14, and the 560 amino acid sequence of SEQ ID NO. 2 is 99 to 100%, wherein the percent homology is represented by the following formula (2):

    {(560-n)/560}×100                                    (2)

wherein n represents the number of different amino acids.
 2. A pair of primers selected from the group consisting of the following (a) to (d):(a) a pair of primer (1) of SEQ ID NO:5 and primer (3) of SEQ ID NO:7; (b) a pair of primer (1) of SEQ ID NO:5 and primer (4) of SEQ ID NO:8; (c) a pair of primer (2) of SEQ ID NO:6 and primer (3) of SEQ ID NO:7; and (d) a pair of primer (PS1) of SEQ ID NO:9 and primer (PS2) of SEQ ID NO:10.
 3. A method for the quality control of an attenuated live varicella vaccine, which comprises performing the method of claim 1 wherein the vaccine is identified as an effective component of an attenuated live vaccine if the vaccine satisfies characteristics (A1) to (A8). 